refactor(i18n): migrate i18n to json format and update configurations

- Rename i18n files to JSON format: en_US.ts -> en_US.json, zh_CN.ts -> zh_CN.json
- Update i18n configurations across multiple config files to use new JSON format
- Remove legacy i18n.ts file
- Update dependencies:
  - @element-plus/nuxt: 1.1.1 -> 1.1.4 - @nuxtjs/i18n: 9.1.1 -> 10.0.1
  - @pinia/nuxt: 0.9.0 -> 0.11.2  - turbo: 2.3.3 -> 2.5.5
- Update package.json scripts and environment variables

Author: terwer

package.json

@@ -22,5 +22,5 @@
     "rimraf": "^6.0.1",
     "turbo": "^2.5.5"
   },
-  "packageManager": "pnpm@9.15.1"
+  "packageManager": "pnpm@10.12.1"
 }